[Carlos9]

I have a question on something that came up. I bought to my knowledge a standard bore 351 block to buid. The block cleaned up good at .040. In the process of putting the thing together and notice more than allowable slack in timing chain. Another assembler recommended I use an undersized timing gear to help take up the slack in the timing chain since he says the block has been line bored. Now to my knowledge as I already mentioned I thought the block was standard which to me also means non line bored. Can this condition happen under normal wear and tear? My mechanic says NO and the block at one time had to have been line bored?

Any thoughts or opinions on this please. I know I need an undersized chain, but what's going on here that would cause this.

[ho-bo woods]

Originally Posted by Carlos9

I have a question on something that came up. I bought to my knowledge a standard bore 351 block to buid. The block cleaned up good at .040. In the process of putting the thing together and notice more than allowable slack in timing chain. Another assembler recommended I use an undersized timing gear to help take up the slack in the timing chain since he says the block has been line bored. Now to my knowledge as I already mentioned I thought the block was standard which to me also means non line bored. Can this condition happen under normal wear and tear? My mechanic says NO and the block at one time had to have been line bored?

Any thoughts or opinions on this please. I know I need an undersized chain, but what's going on here that would cause this.

Hi, Are you using a quality chain set when checking? Try a different brand chain set for fit. Also be very careful with line bore timing sets, you don't want it so tight that it puts a strain on the front main bearing, a little loose is better than to tight. good luck

[Irelands child]

I just had the front of my 5.0 engine apart for other reasons and decided to replace the timing set with Tru-Roller pieces instead of the standard double set. While I do recall assembling the chain, I don't remember it being as tight as I found it - but it probably was. (5.0/302 and 351W's all use the same timing set)

I ended up with a Summit Brand, both gears are billet steel instead of having the cast cam gear. There is a slight bit of slack now, about what I would expect. When I cross checked, that Summit set, the part numbers are all Cloyes.

[Carlos9]

After tearing down and double checking things the issue turned out the be the cheap $75 white box timing chain that my original guy used. We put a ford motorsport chain on and solved the problem. You have to be careful of the parts people use. White box = no good